Communication Examples - Mitsubishi Electric MELSEC iQ-R Series User Manual

Precautions
• When the master/local modules are simultaneously powered on in both systems, the system A (control system) will start as
a master operating station. When a master/local module is powered on in a single system, a system which is powered on
will start as a master operating station. To power on a single system, start up the system so that the system of the master
operating station becomes a control system.
• Do not start up a system with a master/local module mounted by configuring the system B as a control system even if the
previous control system was system B.
• To check the status of standby system master/local module with an engineering tool connected to a control system, use
'Data link status of other stations' (SW0080 to SW0083). If the data link status of the standby system remains in the normal
state (in 'Data link status of other stations' (SW0080 to SW0083) and a bit corresponding to a standby master station is off)
for two seconds or more, the master/local module of the standby system has been started normally.
• Do not set tracking for the link special relay areas (SB0020 to SB01FF), which are turned on/off by the system, or the link
special register areas (SW0020 to SW01FF), where data is stored by the system.
• The remote output (RY) and remote register (RWw) are held until the master operating station switch is completed with the
switching and program.
For details on tracking, refer to the following.
 MELSEC iQ-R CPU Module User's Manual (Application)

Communication examples

This section describes communication examples using the standby master function in a redundant system.
System configuration example
The following system configuration is used to explain the communication examples using the standby master function in a
redundant system.
A same configuration should be used for the control system and standby system of the redundant system.
Master station (control system): Station No.0
Standby master station (standby system): Station No.5
Remote I/O station: Station No.1
Remote I/O station: Station No.2
Remote device station: Station No.3
The program example uses a setting of 80H for the start I/O number of the redundant function module and
40H for the start I/O number of the master/local module.
APPX
180
Appendix 8 How to Use Standby Master Function in Redundant System